Ludwigite Ore Research Articles

Borax preparation from Na-B-Si-containing solution by carbonation and multi-step crystallization

The Na-B-Si-containing solution was derived from ludwigite ore through a two-step process involving soda-ash roasting and subsequent grind-leaching. This study employed a carbonation-crystallization approach to comprehensively utilize the valuable components in the solution, aiming to produce borax while simultaneously generating sodium carbonate and silica. The initial carbonation precipitation achieved a high desilication ratio of 95.54 % through nano-sized silica particle formation. Meanwhile, the boron conversion ratio reached 94 %, with negligible boron loss due to efficient metaborate-to-borate transformation. To guide the crystallization separation of Na2CO3 and Na2B4O7, phase diagrams of the ternary system (Na2CO3 + Na2B4O7 + H2O) were experimentally constructed at 308.15 k and 333.15 k. Crystallization was then conducted at 278.15 K for 2 h, yielding a Na2B4O7·10H2O product with 96.45 % purity. The remaining filtrate was evaporated and crystallized to obtain the Na2CO3 product, which can be reused in the previous roasting process.

Water Leaching Kinetics of Boron from the Alkali-Activated Ludwigite Ore.

The primary aim of this study was to investigate the boron leaching process from alkali-activated ludwigite ore. Initially, the ore underwent activation through roasting at 1050 °C for 60 min with 20% sodium carbonate. Subsequently, the study examined the influence of leaching parameters, including temperature, time, liquid-to-solid ratio, and particle size, using the activated ore as the raw material. Additionally, water leaching characteristics of the residues and boron kinetics were analyzed. The results demonstrated that boron leaching efficiency reached 93.71% from the reduced ludwigite ore under specific conditions: leaching temperature of 180 °C, leaching time of 6 h, liquid-to-solid ratio of 8:1, and feed particle size of 52.31 μm (average particle size). Leach residue characteristics indicated the dissolution of minerals during the process. The boron behavior during water leaching followed the Avrami Equation, and the kinetics equation was derived by fitting the leaching data. Moreover, the activation energy (Ea) value for boron leaching was determined to be 8.812 kJ·mol-1 using the Arrhenius Equation, indicating that the leaching process is controlled by diffusion.

An integrated and efficient process for borax preparation and magnetite recovery from soda-ash roasted ludwigite ore under CO–CO2–N2 atmosphere

An integrated and efficient process for borax preparation and magnetite recovery from soda-ash roasted ludwigite ore under CO–CO2–N2 atmosphere

Microwave-Intensified Separation of Boron and Iron from Ludwigite Ore Based on Impedance Matching

Microwave-Intensified Separation of Boron and Iron from Ludwigite Ore Based on Impedance Matching

A facile route to the value-added utilization of ludwigite ore: boron extraction and MxMg1-xFe2O4 spinel ferrites preparation

The utilization of ludwigite ore is of strategic significance to China. Aiming to realize the comprehensive utilization of ludwigite ore, facile technique route was proposed to selectively leach boron and prepare single-phase metal-doped spinel ferrites via oxidative roasting-water leaching-magnetic separation. The synergistic formation mechanism of sodium borate and metal-doped magnesium ferrites was primarily investigated, and the roasting and leaching parameters on the boron leaching were optimized. The presence of Na2CO3 facilitates the formation and grain growth of ferrites during roasting, and at least 20 wt% Na2CO3 is needed to activate boron efficiently. As the insoluble magnesium borate transforms into soluble sodium borate, the water leaching ratio of boron reaches 95.97%. Subsequently, the high-purity single-phase metal-doped magnesium ferrites were prepared by magnetic separation from the water leaching residue.

A novel process for highly efficient separation of boron and iron from ludwigite ore based on low-temperature microwave roasting

A facile route for simultaneous activation and separation of boron and iron from ludwigite ore at low temperature under the synergistic effect of microwave heating and sodium carbonate (Na2CO3) was reported. It was shown that the composite system would absorb microwave energy well and promote the reduction of iron oxides and formation of water-soluble metaborate derived from szaibelyite, with restrained decomposition of lizardite which demanded less Na2CO3. After roasting at only 700 °C, the metallized briquettes with iron metallization degree (ηFe) of 90.5% were produced. By milling and leaching and subsequent magnetic separation of the metallized pellets, the boron-rich leachate with boron leaching percentage of 85.1% and direct reduced iron (DRI) powders with total iron content (TFe) of 90.6 wt%, ηFe of 97.6%, and iron recovery (εFe) of 91.2% could be obtained. Boron and iron had much better separation performance than that achieved by the conventional route.

Sintering and Smelting Property Investigations of Ludwigite

In this paper, orthogonal experiments are designed to study the sintering and smelting characteristics of the ludwigite ore. The predominant influencing factors of the optimal ratio, basicity and carbon content on different single sintering indexes, including the vertical sintering speed, yield rate, drum strength and low-temperature reduction pulverization index, are firstly explored by the range analysis method, and the main influencing factors on comprehensive indexes are obtained by a weighted scoring method based on different single index investigation. Considering the sintering characteristics, the primary and secondary influencing factors are: ordinary ore ratio, carbon content and basicity, and the optimal ore blending scheme is: basicity 1.7, ordinary ore blending ratio 60% and carbon content 5%. In terms of the smelting characteristics, the research obtains the order of the influencing factors on the softening start temperature, softening end temperature, softening zone, smelting start temperature, dripping temperature, smelting-dripping zone, maximum pressure difference and gas permeability index of the ludwigite sinters by simply considering various single smelting indexes. On this basis, considering the comprehensive softening-melting-dripping characteristics, the primary and secondary influencing factors are: carbon content, ordinary ore ratio and basicity, and the optimal ore blending scheme is: basicity 1.9, ordinary ore blending ratio 60% and a carbon content of 5.5%. Comprehensively, considering the sintering and smelting property of the ludwigite ore, the primary and secondary influencing factors are: carbon content, ordinary ore ratio and basicity, and the optimal ore blending scheme is: basicity 1.9, ordinary ore blending ratio 60% and a carbon content of 5.5%.

Co-Conversion Mechanisms of Boron and Iron Components of Ludwigite Ore during Reductive Soda-Ash Roasting

Ludwigite ore is a typical intergrown mineral resource found in China. Reductive soda-ash roasting followed by water leaching is an innovative process for the high-efficiency separation and recovery of boron and iron. In this study, the co-conversion mechanism of boron activation and iron reduction during soda-ash reductive roasting for boron-bearing iron concentrate was clarified. When the boron-bearing iron concentrate was reduced in the presence of Na2CO3, szaibelyite (Mg2(OH)(B2O4) (OH)) was activated to sodium metaborate (NaBO2) and, meanwhile, magnetite (Fe3O4) was reduced to metallic iron (MFe). Boron activation promoted iron-oxide reduction effectively, while the latter could only slightly influence the former. The promotion occurred through (1) a facilitated generation of sodium magnesium silicate (Na2MgSiO4) and a hindering of the formation of olivine (MgxFe2-x(SiO4)). (2) The newly generated NaBO2 promoted iron-oxide reduction. (3) The low melting point of the NaBO2 (966 °C) favored particle migration, which accelerated metallic iron particle aggregation.

Recycling Excessive Alkali from Reductive Soda Ash Roasted Ludwigite Ore: Toward a Zero-Waste Approach

During the soda ash calcining of ludwigite ore, sodium magnesium silicates are generated accompanying the activation of boron. This leads to the excessive consumption of soda ash and in turn enviro...

Extraction of Boron from Ludwigite Ore: Mechanism of Soda-Ash Roasting of Lizardite and Szaibelyite

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, lizardite and szaibelyite were prepared and their soda-ash roasting behaviors were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analyses, in order to shed light on the soda-ash activation of boron within ludwigite ore. Thermodynamics of Na2CO3-MgSiO3-Mg2SiO4-Mg2B2O5 via FactSage show that the formation of Na2MgSiO4 was preferential for the reaction between Na2CO3 and MgSiO3/Mg2SiO4. While, regarding the reaction between Na2CO3 and Mg2B2O5, the formation of NaBO2 was foremost. Raising temperature was beneficial for the soda-ash roasting of lizardite and szaibelyite. At a temperature lower than the melting of sodium carbonate (851 °C), the soda-ash roasting of szaibelyite was faster than that of lizardite. Moreover, the melting of sodium carbonate accelerated the reaction between lizardite with sodium carbonate.

Stepwise recovery of magnesium from low-grade ludwigite ore based on innovative and clean technological route

Abstract A novel and clean technological route for the comprehensive utilization of low-grade ludwigite ore was proposed, in which magnesium was extracted by metallizing reduction-magnetic separation, sulfuric acid leaching and ethanol precipitation operation. Meanwhile, iron-rich product, silicon-rich product and boron-rich product were obtained, respectively. In the process of metallizing reduction-magnetic separation, 94.6% of magnesium was enriched in the non-magnetic substance from the ore reduced at 1250 °C for 60 min with the ore size of 0.50–2.00 mm and coal size of 0.50–1.50 mm. When the non-magnetic substance was leached at 90 °C for 15 min with the liquid-to-solid ratio of 7:1, 87.4% of magnesium was leached into the liquor separated from silicon gathering in leaching residue. The ethanol precipitation was conducted for 30 min with the ethanol-to-original liquid volume ratio of 1.5:1 at room temperature. 97.2% of magnesium was precipitated out with the initial concentration of 0.8 mol/L in the form of MgSO4·7H2O.

Utilization of the MgO-Rich Residue Originated from Ludwigite Ore: Hydrothermal Synthesis of MHSH Whiskers

In this work, from the MgO-enriched residue originated from ludwigite ore, value-added magnesium hydroxide sulfate hydrate (MHSH) whiskers were prepared via sulfuric acid leaching and leachate purification, followed by hydrothermal synthesis. During sulfuric acid leaching, 98.2% magnesium and 99.6% silica were removed under the optimal leaching conditions: sulfuric acid concentration of 40%, leaching temperature of 80 °C, leaching time of 90 min, and liquid to solid ratio of 4 mL/g. After purification of the acidic leachate via oxidation and precipitation to remove impurities including iron and aluminum, the Mg2+-rich solution was used to prepare magnesium hydroxide sulfate hydrate whiskers (5Mg(OH)2·MgSO4·2H2O, abbreviated as 512MHSH) via hydrothermal synthesis. Finally, 512MHSH whiskers were obtained with 30–100 μm in length, 0.5–1.0 μm in diameter and aspect ratio of approximately 100. The physicochemical characteristics of whiskers were further characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), Fourier Transform Infrared Spectroscopy (FT-IR) and Thermogravimetry-Differential Scanning Calorimetry (TG-DSC).

Water leaching of boron from soda-ash-activated ludwigite ore

Water leaching of boron from ludwigite ore activated by soda ash under reductive, natural and oxidative atmospheres was investigated by evaluating the effects of roasting parameters (roasting atmosphere, temperature and time) and leaching parameters (leaching temperature, leaching time, liquid-to-solid mass ratio and feed particle size) on boron leaching. The presence of CO during soda-ash activation promoted boron leaching because of the reduction of iron-bearing minerals in the ore, whereby iron species within magnetite (Fe3O4) and ludwigite ((Mg,Fe)4Fe2[B2O6]O4) transformed to metallic iron. This facilitated the reaction between B2O3 and soda ash, giving rise to the formation of water-soluble sodium metaborate. The boron of 92.7% could be extracted from the ore roasted in the presence of soda ash (25wt.%) under the 100% CO atmosphere at optimized roasting and leaching conditions.

Comprehensive Utilization of Ludwigite Ore Based on Metallizing Reduction and Magnetic Separation

With the aim of high-efficiency utilization of Dandong ludwigite ore, a new process of metallizing reduction and magnetic separation was proposed, and the effects of reduction temperature, reduction time, carbon ratio, ore size and coal size on the efficiency of the process were investigated in details, and relevant mechanisms were elucidated by SEM and EDS. The optimum technological parameters for metallizing reduction and magnetic separation on ludwigite ore were obtained as reduction temperature of 1 250 °C, reduction time of 60 min, carbon ratio of 1.4, ore size of 0.500–2.000 mm, and coal size of 0.50–1.50 mm. After adopting the optimum parameters, the iron content and recovery ratio of iron in magnetic substance are 87.78% and 88.02%, respectively, while the recovery ratios of boron, magnesium and silicon in non-magnetic substance are 88.86%, 94.60% and 98.66%, respectively. After metallizing reduction and magnetic separation, valuable elements of ludwigite ore could be separated and utilized in subsequent steelmaking process and hydrometallurgy process.

An innovative process for extracting boron and simultaneous recovering metallic iron from ludwigite ore

Ludwigite ore has not yet been utilized on an industrial scale due to its complex mineralogy and fine mineral dissemination in China. Boron–iron separation and dissolution activity of boron-bearing minerals in alkaline liquor are the two key issues in the utilization of ludwigite ore, governing the boron recovery as well as operating cost. This paper proposes an innovative process for extraction of boron and iron from ludwigite ore based on coal-based direct reduction process with sodium carbonate (Na2CO3). The novel process involves reduction roasting, combined leaching and grinding of reduced ludwigite ore, followed by magnetic separation of leach residue, and experimental validation for each of the processing steps is demonstrated. Alkali-activation of boron and metallization of iron were synchronously achieved during carbothermic reduction of ludwigite ore in the presence of Na2CO3. Consequently, boron was readily extracted in the form of sodium metaborate (NaBO2) with water at room temperature during ball mill grinding, and metallic iron powder was recovered from the leaching-filtering residue by magnetic separation. Boron extraction of 72.1% and iron recovery of 95.7% with corresponding iron grade of 95.7% in the magnetic concentrate were achieved when ludwigite ore was reduced with 20% sodium carbonate at 1050°C for 60min.

Oxidation of Silicon and Boron in Boron Containing Molten Iron

A new process of directly smelting boron steel from boron-containing pig iron has been established. The starting material boron-containing pig iron was obtained from ludwigite ore, which is very abundant in the eastern area of Liaoning Province of China. The experiment was performed in a medium-frequency induction furnace, and Fe2O3 powder was used as the oxidizing agent. The effects of temperature, addition of Fe2O3, basicity, stirring, and composition of melt on the oxidation of silicon and boron were investigated respectively. The results showed that silicon and boron were oxidized simultaneously and their oxidation ratio exceeded 90 % at 1 400 °C. The favorable oxidation temperature of silicon was about 1 300–1 350 °C. High oxygen potential of slag and strong stirring enhanced the oxidation of silicon and boron.

Pyrometallurgical Separation of Boron from Iron in Ludwigite Ore.

Laboratory scale experiments and industrial scale tests have been performed in order to develop a new pyrometallurgical process for the separation of boron from iron in ludwigite ore. The results indicate that boron can be effectively separated from iron in ludwigite ore meantime two products can be got. The boron-containing pig iron can be a good substitute for the expensive boron alloys to produce B-series wear resistant cast while the boron-rich slag can be used to extract borax or boric acid.